tooling: Publish repo spec compliance docker container to github packages

[justinabrahms]

See #254 . We should get that auto-publishing for easy docker run ghcr.io/... usage.

[beeme1mr]

@justinabrahms I wonder if we should create a GitHub action to run the spec checker from this repo. We could create a matrix of SDK repos that are checked out and parsed. The output could be aggregated into a report. We could even automatically open issues in repos where gaps are detected.